In semiconductor technology, it is often necessary to change the circuitry of the integrated electronic circuits on semiconductor chips retrospectively to a certain extent. These may be changes that affect only those circuit components that are provided for test purposes. The design of the circuit should thus be as flexible as possible in order to make it possible to produce the required variants of the wiring without any fundamental change to the component structure. It is thus particularly desirable to design the wiring that is provided in the metallization levels on the upper face of the semiconductor chip so that it can be varied in such a way that circuit parts can be adapted to different functions of the circuit with relatively minor modifications. In particular, it is thus possible to activate different test circuits or to provide alternative circuit functions during the production of the semiconductor chips.
However, the flexible circuit design leads to these circuits, including the intended alternatives, occupying more space on the semiconductor chip than is the case with an electronic circuit that is restricted to one specific method of operation. The greater the number of options that are kept open, the larger the surface area required for the circuit generally is.
One possible way to design the electrical connections of the circuit components from the semiconductor chip to be flexible is to make use of the capability to interrupt interconnects, or to electrically conductively connect interconnect ends to one another, by means of so-called fuses and anti-fuses. In the case of interconnects, which are in the form of structures in metallization levels, interruptions can be produced in an interconnect, for example, by using a laser beam, by means of which a part of the metallic interconnect is removed. However, the laser beam can interrupt only relatively coarse interconnect structures, so that a relatively large amount of surface area is consumed for a fuse implementation such as this.
The semiconductor components are generally connected in two or more metallization levels, which are arranged on the semiconductor body, are in each case structured, and are separated from one another by intermediate dielectrics. One variation of the connection of the integrated circuit components can also be provided by designing this connection in such a way that, by changing the structure, only a small number of metallization levels, and preferably only a single metallization level, can be used to provide the required different circuit functions by using an appropriately modified structuring mask. However, this is dependent on at least one mask being designed differently for the semiconductor chips that are processed on the same wafer, or on the relevant masks being replaced when changing the processed wafers. It is generally impossible to retrospectively change the interconnect structure in the metallization levels, since interconnects can be arranged in the upper metallization levels, which must never be removed or even only damaged.